Reverse circulation junk basket

ABSTRACT

An apparatus and method for capturing debris and metal cuttings downhole in a wellbore. Fluid is reverse circulated through a tubing positioned in the wellbore. An aperture opens to a larger space within the tubing interior and creates a pressure drop which separates the debris from the fluid. The debris is separated from the fluid and is collected by an interior space within the tubing. The tubing can be retrieved from the wellbore so that the debris is separated from the interior space.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to completion and repair operationsdownhole in wellbores. More particularly, the invention relates to animproved apparatus and method for capturing metal debris and metalcuttings downhole in the wellbore.

[0002] Metal debris known as “junk” and metal cuttings and otherimpurities are generated during wellbore completion and repairoperations. To create a window in the side wall of wellbore casing,rotating mills are directed by a whipstock or similar device against thecasing interior wall. The rotating mills generate metal cuttings heavierthan the circulating fluid. Other types of rotating mills remove packersand broken equipment from a wellbore and clear obstructions from thewellbore. Metal cuttings from such operations restrict wellboreproduction and encumber tool movement through the wellbore.

[0003] “Junk baskets” operate with mills to capture debris and metalcuttings during wellbore completions and milling operations. Junkbaskets are typically positioned on the drill stem exterior surface asshown in U.S. Pat. No. 3,814,180 to Oliver (1974), which disclosed ajunk basket surrounding the tubular above a drilling bit. U.S. Pat. No.3,907,047 to Thompson et al. (1975) disclosed a junk basket attached toa rotary drill bit which included an annular cup. U.S. Pat. No.4,111,262 to Duncan (1978) disclosed a flexible junk boot clamped to thedrill string exterior. U.S. Pat. No. 4,217,966 to Garrett (1980)disclosed a metal cup spindled on a drill bit pin so that the cup wasautomatically dumped each time that the drill bit was removed from thestem. Additionally, U.S. Pat. No. 4,390,064 to Enen et al. (1983)disclosed a releasable junk basket attachable to the drilling stringexterior

[0004] Certain junk baskets operate movable sleeves to collect debriswithin a chamber. U.S. Pat. No. 5,135,050 to Tailby (1992) disclosed apiston-like sleeve for use in horizontal wells which was releasable toopen ports for collecting a quantity of debris in a chamber. Other junkbaskets use magnets to attract and capture metal fragments and cuttings.U.S. Pat. No. 4,059,155 to Greer (1977) disclosed a magnet assembly in alongitudinally extending passageway for capturing metal fragments. U.S.Pat. No. 5,944,100 to Hipp (1999) disclosed magnets attached to a toolbody and flexible fingers or brushes to move the debris from the magnetstoward a storage area.

[0005] Although most junk baskets are located exterior of the tubular,U.S. Pat. No. 4,276,931 to Murray (1979) disclosed a junk retainingmeans located within a tubular body. “Catchers” having pivoted fingerswere located above the milling teeth for capturing metal debris. Areduced fluid pressure for drawing junk into a chamber was created byactivating inwardly extending fluid jets. The jets were supported by ajet housing and were activated by a pressure responsive activating meansto capture junk within the wellbore.

[0006] The proliferation of multilateral wells and complex wellborecompletion systems increases the need for milling operations inwellbores. Increasingly close tolerances in valves and well controlequipment requires tight control over debris in the wellbores.Additionally, conventional debris capture systems do not always providefor selective fluid pressure control within a selected wellborelocation. Accordingly, a need exists for an improved method andapparatus for capturing metal cuttings and other debris downhole in awellbore.

SUMMARY OF THE INVENTION

[0007] The present invention provides an apparatus and method forcapturing debris downhole in a wellbore when fluid is reverse circulatedthrough the wellbore. The apparatus comprises a hollow basket housingattached to said tubular, a basket member positioned within the baskethousing to define an interior volume between the basket housing and thebasket member for capturing the debris, and an aperture in the basketmember for permitting reverse circulated flow of the fluid and debristherethrough, wherein the aperture has a dimension smaller than aninterior dimension of the hollow tubular to generate a pressure dropproximate to the basket member to facilitate separation of the debrisfrom the fluid.

[0008] In another embodiment of the invention, the apparatus comprises ahollow tubular operable from the wellbore surface, a cutter head, and abasket attached between the cutter head and the tubular, wherein thebasket comprises an exterior housing and an interior member having anaperture for permitting flow of the fluid and debris therethrough, andwherein the interior member and the exterior housing form an interiorvolume for capturing the debris as the fluid and debris are reversecirculated through the aperture.

[0009] The method of the invention comprises the steps of attaching abasket housing to a tubular to define an interior volume within thetubular, wherein the basket housing includes an aperture for permittingfluid flow therethrough, of positioning the tubular and basket housingdownhole in a wellbore, of reverse circulating fluid to move the debristhrough the aperture, and of separating the debris from the fluid as thedebris and fluid passes through the aperture so that the debris iscaptured within the basket housing interior volume.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010]FIG. 1 illustrates an elevation view of an aperture in a baskethousing having an interior volume for capturing debris.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The invention provides an apparatus and method for capturingdebris downhole in a wellbore. The invention is particularly suited forcapturing metal filings generated during milling operations.

[0012]FIG. 1 illustrates one embodiment of the invention wherein tubular10 formed with one or more sections is positioned within wellbore 12.Basket 14 is attached to tubular 10 and generally comprises baskethousing 16 and basket member 18. Basket housing 16 has threadforms 20and 22 for integral connection to tubular 10. Basket housing 16 isformed with lower section 24 and upper section 26 connected withthreadform 28. The interior wall of basket housing 16 is cylindricalwith a diameter substantially similar to the interior diameter oftubular 10 in a preferred embodiment of the invention. However, theshape, configuration and dimensions of tubular 10 and of basket housing16 can be shaped in different ways to accomplish different designcriteria, however basket housing 16 is hollow to permit the passage offluid and of debris therethrough..

[0013] An interior member or basket member 30 is attached to baskethousing 16 for the purpose of constricting fluid flow through aperture32 and for the purpose of forming interior volume 34. As shown in FIG.1, collar 36 is retained between surfaces 38 and 40 on lower section 24and on upper section 26 respectively. Collar 36 has aperture 32therethrough and is attached with threadform 42 to sleeve 44. Theexterior surface of sleeve 44 and the interior wall of upper section 26define a toroidal shaped space identified as interior volume 34.Interior volume 34 has closed end 46 and open end 48. Although interiorvolume 34 is formed as a toroid, the configuration, shape, orientationand relative size of such component can be varied to accomplishdifferent design objectives.

[0014] As shown in FIG. 1, mill 50 can be attached to threadform 22 togenerate metal cuttings in wellbore 12. If tubular 10 is rotatable fromthe surface of wellbore 12, mill 50 will not require additional drivecomponents.

[0015] Reverse circulation of fluid 52 in the direction shown willtransport debris such as junk or metal cuttings upwardly throughaperture 32. Sloped surface 54 can direct fluid 52 and the metalcuttings toward aperture 32. As fluid 52 and the transported metalcuttings travels through aperture 32 and exits through sleeve 44 intothe interior of upper section 26, the pressure of fluid 52 is reducedand the flow rate is correspondingly decreased. At such location thetransported metal cuttings separate from fluid 52 and fall by gravityinto interior volume 34. Fluid 52 moves upwardly from the captured metalcuttings as fluid 52 is circulated through tubular 10.

[0016] The invention is particularly suitable for the purposes ofwashing pipe and tubing connections, and can be run to mill over junk orthrough packers to prevent mill cuttings from falling downwardly andbeing re-milled. By effectively capturing the metal cuttings, the usefullife of a mill shoe such as mill 50 will be extended, therefore reducingthe number of trips necessary to replace mill 50.

[0017] The invention is also useful if the wellbore 12 is losing fluiddownhole because fluid 52 can be reverse circulated with low pressure.As the metal cuttings tend to fall downwardly through gravity, the metalcuttings are captured within interior volume 34 and do not reach mill50.

[0018] The invention can be used with a hydro-static baller or mud pumpfor light milling operations or to retrieve small pieces of debris orjunk that would otherwise flow through a drain sub or flapper valve. Theinvention can be used to mill up loose debris and bridge plugs and canbe run with a drill bit or mill. The invention is particularly suitablewith a whipstock in milling operations which form a window in exteriorcasing pipe set in wellbore 12.

[0019] Although the invention has been described in terms of certainpreferred embodiments, it will become apparent to those of ordinaryskill in the art that modifications and improvements can be made to theinventive concepts herein without departing from the scope of theinvention. The embodiments shown herein are merely illustrative of theinventive concepts and should not be interpreted as limiting the scopeof the invention.

What is claimed is:
 1. An apparatus for capturing debris downhole in awellbore when fluid is reverse circulated through the wellbore andthrough a hollow tubular positioned in the wellbore, comprising: ahollow basket housing attached to said tubular; a basket memberpositioned within said basket housing to define an interior volumebetween said basket housing and said basket member for capturing thedebris; and an aperture in said basket member for permitting reversecirculated flow of the fluid and debris therethrough, wherein saidaperture has a dimension smaller than an interior dimension of thehollow tubular to generate a pressure drop proximate to said basketmember to facilitate separation of the debris from the fluid.
 2. Anapparatus as recited in claim 1, wherein said basket housing isdetachable from the tubular to permit removal of the debris from saidinterior volume.
 3. An apparatus as recited in claim 1, wherein saidbasket member is substantially cylindrical.
 4. An apparatus as recitedin claim 1, wherein said basket member further comprises a slopedsurface proximate to said aperture for guiding fluid and debris throughsaid aperture.
 5. An apparatus as recited in claim 1, wherein saidinterior volume is substantially toroidal with a closed end and an openend for permitting entry of the debris into said interior volume.
 6. Anapparatus for capturing debris downhole in a wellbore when fluid isreverse circulated through the wellbore, comprising: a hollow tubularoperable from the wellbore surface; a cutter head; and a basket attachedbetween said cutter head and said tubular, wherein said basket comprisesan exterior housing and an interior member having an aperture forpermitting flow of the fluid and debris therethrough, and wherein saidinterior member and said exterior housing form an interior volume forcapturing the debris as the fluid and debris are reverse circulatedthrough said aperture.
 7. An apparatus as recited in claim 6, whereinsaid basket is detachable from said tubular to facilitate removal of thedebris from said basket interior volume.
 8. An apparatus as recited inclaim 6, wherein said basket is detachable from said cutter head tofacilitate removal of the debris from said basket interior volume.
 9. Anapparatus as recited in claim 6, wherein said interior member issubstantially cylindrical.
 10. An apparatus as recited in claim 6,wherein said interior member further comprises a sloped surfaceproximate to said aperture for guiding fluid and the debris through saidaperture.
 11. An apparatus as recited in claim 6, wherein said interiormember further comprises a ring having a threadform for detachableengagement with said exterior housing.
 12. A method for capturing debrisdownhole in a wellbore, comprising the steps of: attaching a baskethousing to a tubular to define an interior volume within said tubular,wherein said basket housing includes an aperture for permitting fluidflow therethrough; positioning said tubular and basket housing downholein a wellbore; reverse circulating fluid to move the debris through saidaperture; and separating the debris from the fluid as the debris andfluid passes through said aperture so that the debris is captured withinsaid basket housing interior volume.
 13. A method as recited in claim12, wherein said basket housing is positioned at a selected locationwithin the wellbore.
 14. A method as recited in claim 12, furthercomprising the steps of withdrawing said basket housing from thewellbore and of removing the debris from said basket housing interior.15. A method as recited in claim 12, further comprising the steps ofoperating a mill to generate metal cuttings within the wellbore and ofcapturing the metal cuttings within said basket housing interior volume.16. A method as recited in claim 12, further controlling the flowrate ofthe circulating fluid to control the density of debris captured withinsaid basket housing interior volume.
 17. A method as recited in claim12, further comprising the step of selecting the aperture dimension tocontrol the fluid pressure drop though said aperture as the debris andfluid flows therethrough.
 18. A method as recited in claim 12, furthercomprising the step of selecting the aperture configuration to directthe debris toward said basket housing interior volume.